CVE-2026-20539 Denial of service in MediaTek chipset

Medium 5.3 Published 5 Oct 2026 Updated 5 Oct 2026

A missing bounds check in MediaTek modem firmware allows remote attackers to cause denial of service via a rogue base station.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-20539?

CVE-2026-20539 is a medium-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 5 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In Modem, there is a possible out of bounds read due to a missing bounds check. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01774038; Issue ID: MSV-8913.

Weakness: CWE-126

Which versions are affected by CVE-2026-20539?

It affects 83 products.

Products include Mediatek Mt2716 Firmware, Mediatek Mt2735 Firmware, Mediatek Mt2737 Firmware, Mediatek Mt6739 Firmware, Mediatek Mt6761 Firmware, Mediatek Mt6762 Firmware and 77 more.

How do I fix CVE-2026-20539?

No fix has been published for CVE-2026-20539 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-20539 being exploited?

There is no known exploitation of CVE-2026-20539 in the wild and no public exploit code.

Sources

Also known as GHSA-gx55-632p-3gpx.